aluminum axles scare me as an engineer. the only way to really get similar strength would be to increase overall diameter of it... as in compltely different swingarm, bearing carrier & much larger bearings & seals to match... then to make it lighter they would be able to hollow it out.
the big problem on all axles is fatigue... which all components of aluminum are severely prone to, even in non-stressed applications. every time an axle makes a rotation the surface goes from tensile stress(bottom) to compressive stress(top) in a cyclical manner.... which causes fatigue. also, when the quad hits any bump, jump, etc, it causes a significant stress riser, specifically near the center, just outside of the bearing carrier... when & if you see an axle break it will be at this location every time, almost guaranteed... this is also why most axles taper at the ends.

i ride dunes and i'm currently running a durablue X-33, which is made of a high tensile steel, but it is also hollow to reduce weight(about 12 lbs). it can handle everything i will throw at it(lots of whoops & small jumps), but i'm not jumping 80' doubles... and it's not made for it either. i don't like the fact that the warranty is limited or the pin-drive hubs, so i may sell it to get a lonestar. mechanically speaking the design of the x-33 could be improved, and weight even reduced more, but i would want them to pay me for the engineering work.


7075 t-6 aluminum is the strongest alloy available in aluminum, but it too is still prone to fatigue, in a big way. tensile strength of this alloy matches a mild mormalized steel, but is nothing compared to a titanium or high strength micro-alloyed steel(i.e 4130 or 4340)that's heat treated properly. titanium's problem is the fact that it is very brittle(won't deflect much at all before it breaks), not to mention a real pain to work with(machining, welding, etc.) and it is more dense than aluminum.

conclusion: an aluminum axle would be great for a dedicated dragger, on reasonably smooth surfaces, reducing unsprung weight and rotating mass greatly.

the decision is still up to you, but i'd stay away from it

 

Thanks for the excellent reply. Lonestar's aluminum axles are thicker and use a larger bearing and carrier. The one I was considering was stock thickness. My biggest fear was time. It may not break instantly, but over time it most likely will.

 

I run an LSR Axcaliber in my R. I race MX. I have never had one single problem with it. (Although it is bent) Its not enough that it matters. The next axle i get will be a RPM Dominator though.